Centrifugal core latch for pipe casting machines



y 8, 1963 P. L. ARNOLD ETAL 3,091,009

CENTRIFUGAL CORE LATCH FOR PIPE CASTING MACHINES Filed 001'.- 20, 1960 2 Sheets-Sheet 1 /|a 2| 4 32 l9 x 4 13-? 1?: .J: zi' f 6, F, I l4 Is I 7 5 3| 5 I2 I2 27 2 3 1 2 I FIG.3

INVENTORS PAUL L, ARA/0L0 WILL/44 ,4. Ma/uraomszv Y ATTORNEY y 1963 P. L. ARNOLD ETAL 3,091,009

CENTRIFUGAL CORE LATCH FOR PIPE CASTING MACHINES Filed Oct. 20, 1960 2 Sheets-Sheet 2 INVENTOR AUL L. Ara/0L0 MLL/AM ,4. MouraomfEY ATTORNEY 3,01,0tl9 CENTREUGAL CORE LATCH FDR PilE CASTING MACIENES Paul L. Arnold and William A. Montgomery, Hayward, Calif., assignors to United States Pipe and Foundry glompany, Birmingham, Ala, a corporation of New ersey Filed Get. 2t 1966, Ser. No. 63,900 4 Claims. (Cl. 22-65) This invention relates to apparatus for use in the centrifugal casting of tubular articles such as cast iron pressure pipe. More particularly the invention is concerned with an improved means for securing a core or other end forming device in place at the bell end of the spinning mold during the casting operation.

In the De Lavaud process for casting cast iron pressure pipe, the pipe is cast in a spinning cylindrical metal mold which is provided with a bell cavity in one end into which is inserted the sand core which forms the inside contour of the bell end of the pipe. The sand core is held in place by means of a metallic backing plate and wedges which are driven into radial holes around the periphery of the mold. During casting, rotation of the mold causes these wedges to hold tight under the action of centrifugal force.

In operation, the core and metallic backing plate are set in place and the wedges hand driven by the core setter. After the core is securely in place, the mold, which is rotatably mounted on a carriage which is movable longitudinally, is moved over a long pouring trough which extends the length of the mold. As molten metal pours from the end of the trough it is distributed along the length of the spinning mold by retracting the mold from the pouring trough at a predetermined rate. After the metal is poured into and distributed along the mold, the mold is kept spinning until the metal has solidified. The spinning mold is then stopped and the core setter then knocks the Wedges loose with a hammer and removes the backing plate. The pipe is then extracted by holding it stationary while the mold is moved longitudinally over the pouring trough, after which, the mold is again retracted from the pouring trough to a position where the core setter is situated to permit the setting of another core and the start of another cycle.

From the above discussion, it is apparent that the casting rate depends upon the length of time it takes to complete a cycle since only one pipe can be cast on a single machine at one time. Thus if the casting rate is to be increased every operation in the cycle must be carried out in the minimum of time. The placing of the core and backing plate into the bell socket, the inserting and driving of the wedges into the holes in the mold and the removal of the wedges after the pipe is cast require an undesirably long time. This time also varies considerably from cycle to cycle because of the human element involved. Accordingly, a more rapid means of setting and securing the core which also reduces the human element involved has long been needed in order to assure maximum casting rates. 'It is the object of our invention to provide a device which satisfies these needs.

More specifically it is the object of our invention to provide core latches which are operated by centrifugal force and which are mounted in a modified mold bell flange.

Another object of our invention is the provision of core latches which are under spring bias which permits the latches to be pushed out of the path of the core as it is inserted into the bell cavity of the mold and assures their return to latching position once the core is in place.

Other objects and advantages of the invention will be obvious from a reading of the specification in conjunction with the drawings of which:

'fi lflfl Patented May 28, 1963 FIGURE 1 is a longitudinal cross section of the bell end of a De Lavaud casting machine modified to incorporate the centrifugal core latch of the invention.

FIGURE 2 is a transverse view of the mold flange with a cut-away portion showing the location of the core latch in the flange.

FIGURE 3 is a longitudinal cross section of the bell end of a De Lavaud casting machine incorporating another embodiment of the invention.

Referring to FIGURE 1, the mold 1 is rotatably mounted in water box 2 which is provided with an end flange 3. The mold is driven through gear ring 4 which is clamped to the mold by means of ring 5 and mold flange 6 in the same manner as is in common practice. The mold flange '6, although serving the same purpose as it generally Sl'VS, is considerably modified over known designs in order to accommodate the mechanism of our invention.

The mold flange 6 consists of a metal ring with a peripheral groove in which centrifugal core latching means are mounted. In other words the mold flange 6 comprises two parallel flanges 8 and 9 which are joined and bridged by the main body 7. The bridge 7 is pierced by a multiple number, forexample, four, equally spaced, radially extending ports 10. Through each port It extends a pin 11 which is provided at its radially innermost end with a bevel 12. At the opposite end the pin is provided with an enlarged head 13 which prevents the pin from slipping through the port 14} and limits the extension of the pin past the bell cavity periphery. 1n the end of pin '11 having the enlarged portion 13, a hole 14 is drilled on the longitudinal axis and extends for less than the full length of pin 11. A coil spring 15 is placed at the bottom of hole 14 and pin 17 is inserted after the spring 15. Pin 17 is provided with a large head 18 which is larger in diameter than the head portion 13 of pin .11. A second coil spring 19 is placed around head portion '13 and under large head 18. The bias tension in springs 15 and 19 keeps the bevel portion 12 of pin '11 pressed against the core ring '20 of core 26 and the head portion 1 8 of pin -17 pressed against finger 21 of the flyweight 22.

Turning to FIGURE 2, the flyweight 22 is rotatably mounted on pin 23 which extends from flange 8 to flange 9. The flyweight is designed so that the predominant portion of its weight is in end '24. The other end of the flyweight is shaped into a finger which is positioned to make contact with the large head 13 of pin 17. A shield 25 is provided over the groove around the periphery of the mold flange to prevent fouling of the centrifugal mechanism by slingout metal or other objects.

In operation, the core 26 which is provided with a core ring 21} which has a frusto-conical peripheral surface 27 is inserted into the mold 1. In the process of inserting the core 26 into the mold the slope of surface 27 in conjunction with bevel surface 12 of the latching pin 11 produce a wedge effect which forces pin 11 radially outward. The radial movement is taken up in spring 15 as pin 11 moves over pin 16. As soon as the core passes beyond the latching pin 11 to the seated position as shown in FIGURE 1, the tension in spring 15 forces pin 11 radially inward until the beveled end protrudes radially inward beyond the outer edge of the core ring. This secures the core in place and prevents it from falling out of the mold While it is at rest.

The mold is then brought up to rotating speed for the casting operation to follow. As the mold spins, the heavy end 24 of the flyweight is subjected to a centrifugal force, and since it is rotatably mounted about a fixed pin 23 it can only rotate counterclockwise around this pin. As the flyweight rotates, finger 21 which is in contact with head 18 presses radially inward on pin 16 to press against spring 15 which in turn exerts a force on latching pin 11.

' combined together into one piece.

As the flyweight 22 continues to rotate, the head 18 comes in contact with head 13 of the latching pin 11 which firmly holds the core in place.

After the pipe has been cast and mold rotation 18 stopped, the flyweight 22 is forcedto rotate clockwise by the outward force of head 18 pressing on finger 21. This outward force is due to the compression in springs 15 and 19 which overcomes the mass of the flyweight as the centrifugal force approaches Zero with the stopping of mold rotation. As the pipe is extracted from the mold, the core ring 29 presses against the bevel end of pin 11. The wedge action between these two surfaces causes an outward movement of pin 11 which increases the bias tension in spring 15 and permits the core ring to slip past the latch pin. As soon as the core ring is free of the latch,

the increased bias tension in spring 15 again forces the pin 11 radially inward until it protrudes inward beyond the core seat in the mold.

In the embodiment shown in FIGURE 3, the latching pin 31 is provided with cut out portions 32 into which twin fingers 33 on the end of the flyweight extend. A bias spring 35 surrounds the cut down radially outer end of the pin and a stud 36 at the very end of the latch pin extends through a fixed bracket 37. A castellated nut 38 is started on the stud and locked in place by cotter pin 39. This nut is not tightened on the stud but only serves to restrict the movement of the latch pin over a fixed distance.

In operation, the flyweight operates in the same manner as the flyweight shown in FIGURE 2 to hold the pin firmly against the core ring. When the core is pushed into position, the sloped surface of the outer periphery of the core and the beveled end of the latch pin produce a wedge effect to move the latch pin 31 radially outward against bias spring 35. As soon as the core ring passes by the latch pin the bias spring forces the latch pin radially inward until it is firmly against the core ring. If the core is to be latched in place when the mold is at rest, it is obvious that spring 35 must be stiff enough to prevent the Weight of the flyweights in the top two quadrants from moving the pins outward. During mold rotation, the castellated nut 38 in cooperation with bracket 37 restricts the inward movement of the latch pin 31. When mold rotation is stopped, the flyweight exertsonly a small radially inward or outward force on the latch pin. The force exerted, of course, depends on where the latch is located around the periphery of the mold flange. Latches located in the upper two quadrants will tend to exert an outward force on the pins and latches located in the lower two quadrants will tend to exert an inward force on the pins.

When the pipe is pulled from the mold the core ring pressing against the beveled end surface of the latch pin forces the latch pin outward to permit withdrawal of the core ring and the pipe from the mold. After the core ring is withdrawn, the compression between the large portion on the pin and the fixed bracket of the bias springs forces the pins inward to locking position. The insertion of a core into the mold forces the pins outward after which the springs cause the pins to spring back to latching position.

It will be understood that the invention is not to be limited by the particular embodiments described and shown which have been set forth merely by way of example. Thus any design for the latching pins which permits the application of a force from the flyweight in a radial direction and restricts the movement of the pin to the desired extent may be used. Of course, the configuration and location of the bias springs can readily be altered, and the latch pin and flyweight may even be Therefore, it is intended that the invention shall not be limited to the specific embodiments shown and described but shall also include all alternate and equivalent structures which fall within the purview of the claims.

We claim:

1. A centrifugal core latching mechanism for use with horizontal cylindrical molds comprising a mold flange having a tapered bore into which a core having a fumeconical outer periphery may be inserted, a multiplicity of radial ports extending from the bore to the outer periphery of the flange, a latching pin extending through each of said radial ports, said latching pin having a bevel on its radial- 1y inward end, which is adapted to co-operate with the frusto-conical outer periphery of said core to move said pin outward when the core is moved across it, stop means for limiting to a predetermined amount the extension of the latching pins beyond the tapered bore surface of the mold flange, a spring bias means exerting a radially inward force on the latching pins at all times, and a centrifugal flyweight at each latching pin which forcesthe latching pin radially inward during mold rotation whereby the core is locked firmly in place.

2. A centrifugal core latching mechanism for use with horizontal cylindrical pipe molds comprising a mold flange adapted to be mounted at the bell end of the mold, said flange having a tapered bore into which a bell core having a frusto-conical outer periphery may be inserted, a multiplicity of radial ports joining the peripheral surface with the said tapered inner bore of said flange, a latching pin extending through each of said radial ports and having a bevel on its radially inward end and a stop means at the opposite end, said bevel being'provided to co-op: erate with the frusto-conical outer surface of the bell core to move said pin outward when said core is movedacross said pin and said stop means limiting the extension of the pin inwardly beyond the surface of said tapered bore to a predetermined amount, spring bias means exerting an inward force on said latching pin at all times, and a centrifugal flyweight mounted at each latching pin and having a heavy end and an opposite lighter end adapted to press against a suitable bearing surface provided on said latching pin, said flyweight being mounted rotatably about an axis parallel to the longitudinal axis of the mold so as to exert an inward force on said latching pin during rotation of said mold.

3. A centrifugal core latching mechanism for use with horizontal cylindrical pipe molds comprising a mold flange adapted to be mounted at the bell end of the mold, said flange having a tapered bore, the circumferential surface of said flange having two radially extending axially spaced flanges which form an annular groove in the outer surface of the mold flange, a multiplicity of radial ports joining the bottom of said annular groove with said tapered inner bore of said flange, a latching'pin extending through each of said radial ports and having a bevel on its radially inward end and an enlarged headat the opposite end, said enlarged head limiting the extension of the pins inwardly beyond the surface of said tapered bore, each latching pin having an axial bore extending less than the length of the latching pin from the end having said enlarged head, a first coiled Spring seated in the bottom of each axial bore, a second pin inserted after said first coiled spring, said second pin having a large head which is larger than the enlarged head of the latching pin, a second coiled spring surrounding said enlarged head of the latching pin and compressed between the bottom of said annular groove and the large head of said second pin, and a centrifugal flyweight pivotally mounted between said axially spaced flanges at each of said pins, said flyweight having a heavy end opposite a light finger shaped end, each flyweight be ing mounted so that the spring tension in said second coil spring firmly presses said large head of said second pin firmly against the finger end of said flyweight.

4. A centrifugal core latching mechanism for use with horizontal cylindrical pipe molds comprising a mold flange adapted to be mounted at the bell end of the mold, said flange having a tapered bore and a multiplicity of radial ports joining said tapered bore with the outer periphery of said flange, a bracket radially spaced from the peripheral entrance of said port, a latching pin extending through each radial port, said pin having a bevel on its radially inward end and a portion of reduced diameter at its outer end, stop means co-operating with said bracket to limit the extension of the pin inwardly beyond the surface of said tapered bore, a coil spring encircling the end portion of reduced diameter and exerting a radially inward force on the pin at all times, said coil spring being mounted between the radially inward side of said bracket and the shoulder formed by the junction between the portion of reduced diameter and the main portion of the latching pin, and a flyweight mounted at each latching pin so as to exert a radially inward force on said latching pin during rotation of said mold.

References Cited in the file of this patent UNITED STATES PATENTS 1,809,631 Ladd June 9, 1931 2,757,033 Noca July 31, 1956 2,838,815 Duval June 17, 1958 3,004,314 Beyer Oct. 17, 1961 

1. A CENTRIFUGAL CORE LATCHING MECHANISM FOR USE WITH HORIZONTAL CYLINDRICAL MOLDS COMPRISING A MOLD FLANGE HAVING A TAPERED BORE INTO WHICH A CORE HAVING A FRUSTOCONICAL OUTER PERIPHERY MAY BE INSERTED, A MULTIPLICITY OF RADIAL PORTS EXTENDING FROM THE BORE TO THE OUTER PERIPHERY OF THE FLANGE, A LATCHING PIN EXTENDING THROUGH EACH OF SAID RADIAL PORTS, SAID LATCHING PIN HAVING A BEVEL ON ITS RADIALLY INWARD END, WHICH IS ADAPTED TO CO-OPERATE WITH THE FRUSTO-CONICAL OUTER PERIPHERY OF SAID CORE TO MOVE SAID PIN OUTWARDLY WHEN THE CORE IS MOVED ACROSS IT, STOP MEANS FOR LIMITING TO A PREDETERMINED AMOUNT THE EXTENSION OF 